Wooden poles are widely used for supporting overhead power and communication lines. A great number of these wooden utility poles are in use in remote locations difficult to access by any type of equipment. Although the majority of the poles have been treated to retard decay, the primary reason for replacing such poles is caused by decay at or near groundline. Reasons for decay include preservatives, that do not penetrate to the center of the pole, soil that may contain a particularly aggressive chemical content, or biological agents. The decay or deterioration puts at risk the structural integrity of the pole. Similar damage to the structural integrity of the pole could be caused by weather, insects, birds, rodents, or other animals. This damage may occur anywhere along the length of the pole and not just at groundline.
Although such damage might not occur to a non-wooden pole, wooden poles are widely utilized because of the ready availability and relative inexpense of materials. In addition to this, metal poles are also susceptible to damage from weather and ground conditions.
Many methods have been proposed in the prior art for repairing such damaged standing poles. In the beginning, the unsound standing pole was simply removed and replaced with a new pole. This is impractical due to the labor and time consuming requirement for removing the power or communications lines carried by the pole.
One prior method of repair involves pole reinforcement, which can be done by setting a wooden stub by the weakened pole and binding the stub to the pole. A variation of this method is also disclosed in U.S. Pat. 3,938,293. This patent depicts an apparatus for installing a driven splint adjacent to a weakened pole. The large driving apparatus required and complicated steps of the method are not cost effective, and therefore the method of this patent would rarely be chosen, except for locations that can be easily reached by heavy equipment, and then only for poles where a repair without a disruption of the services or necessity for otherwise supporting or disengaging the power or communications lines is required.
Another prior repair method involves cutting off the pole above the damaged, embedded lower portion, supporting the pole and the power or communications lines that it carries, and then removing and replacing the base of the pole with some type of replacement footing. An example of this technique is disclosed in U.S. Pat. 4,621,950 and its related U.S. Pat. 4,618,287. The disadvantages of this method are also readily apparent. In fact this is not an improvement over the method of simply replacing the standing pole because of the need to support the pole during the replacement of the damaged lower end. In addition this method has not been proven to be cost competitive with a simple replacement of the damaged pole with a new pole. The requirement of a large truck mounted with complicated machinery is also shared by these methods.
A similar repair method is disclosed in U.S. Pat. No. 4,033,080 which discloses a method of replacing the lower part of a wooden pole with a concrete segment to be embedded in the ground. In order to make this repair, the existing pole must be cut in two, the upper part of the pole supported, and lower part of the pole pulled from the ground prior to the installation of the concrete base, which is driven into the ground. This method has the same drawbacks as that previously described U.S. Pat. Nos. 4,618,287 and 4,621,950.
Yet another method is disclosed by U.S. Pat. No. 4,371,018. This reference discloses an apparatus for lengthening or shortening poles. The method involves raising the pole vertically until its lower end is clear of the ground so that a replacement for the lower end can be attached, afterwards the pole and the replacement are joined together, after which the pole and stub are lowered vertically into the ground to the required depth. The ground is then consolidated to complete the repair. In addition to the disadvantages discussed and readily apparent that this method shares in common with the previous described references, this reference discloses a complicated and expensive device which must be mounted on a heavy piece of equipment and must be used in the field.